Page 130 - 水利学报2021年第52卷第5期

Moisture and multi-ions transport in concrete under drying-wetting cycles：
a numerical study

1 1，2
CHEN Weikang ，LIU Qingfeng
（1. State Key Laboratory of Ocean Engineering，School of Naval Architecture，Ocean & Civil Engineering，
Shanghai Jiao Tong University，Shanghai 200240，China；
2. Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure，Shanghai 200240，China）

Abstract：The durability problems of concrete structures subjected to drying-wetting cycles are very promi⁃
nent. Chloride transport in unsaturated concrete is mainly affected by the convection due to moisture trans⁃
port. Meanwhile， since the concrete pore solution always contains multiple ionic species， the electrochemi⁃
cal coupling effect between different species on chloride transport is non-negligible. In this study， the ef⁃
fects of electrochemical multi-species coupling and convection are emphatically considered， and a coupled
transport model of moisture and multiple ions in unsaturated concrete is established， which is verified by
the third-party experiments. Though numerical study， it is found that the electrochemical coupling effect
during drying-wetting actions would generate spatial-temporal electrostatic potential within concrete porous
solution and markedly affects the prediction of ionic transport. After 10 times of drying-wetting cycles，the
chloride content considering multi-species model is 1.26 times as compared to considering single-species
model. The decrease of the time ratio of drying to wetting， the increase of the drying-wetting cycles， and
the decrease of the water boundary saturation during the drying process could all enlarge the influence of
the electrochemical coupling on chloride transport. The results show that considering a single-species trans⁃
port will lead a lower prediction of chloride intake under drying-wetting conditions, which will result in a
more dangerous durability design of concrete.
Keywords： drying-wetting cycles； unsaturated concrete； moisture； multi-species； chloride； electrochemical
coupling
（责任编辑：韩 昆）

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Vibration trend prediction of hydroelectric generating unit based on MIC and BiGRU

BI Yang ，ZHENG Bo ，ZHANG Yawu ，ZHU Xi ，
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JIANG Yalan ，LI Chaoshun
（1. Zhejiang Xianju Pumped-storage Power Co.Ltd，Xianju 317300，China；
2. PowerChina Huadong Engineering Corporation Limited，Hangzhou 311122，China；
3. State Grid Xinyuan Company Ltd.，Beijing 100761，China；
4. School of Hydropower and Information Engineering，Huazhong University of Science and Technology，Wuhan 430074，China）
Abstract：To improve the accuracy of vibration trend-prediction for hydropower unit，a novel trend-predic⁃
tion approach is proposed based on maximal information coefficient （MIC） and bidirectional gate recurrent
unit （BiGRU） network. Initially， wavelet threshold de-noising （WTD） method is applied to reduce the
strong noise of historical vibration data. Then， the MIC algorithm is used to select the strongly correlated
status parameters，which influenced by hydraulic，electrical factors and mechanical unbalanced force. Then，
BiGRU network is employed to establish the vibration trend-prediction model， and the trend prediction of
vibration signals is carried out with multistep in advance. The trend-prediction of vibration signal obtained
online is predicted by the trained model. In order to evaluate the prediction performance of the model，the
vibration monitoring data of a pumped storage hydropower station are collected for multiple groups of com⁃
parative experiments， which proves that the proposed method has good prediction ability and generalization
ability，which is suitable for the trend prediction of vibration of hydropower units.
Keywords： maximal information coefficient （MIC）； bidirectional gate recurrent unit （BiGRU）； wavelet
threshold de-noising （WTD）；signal processing；feature selection；trend prediction
（责任编辑：杨 虹）
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